US4297149A - Method of treating SiPOS passivated high voltage semiconductor device - Google Patents

Method of treating SiPOS passivated high voltage semiconductor device Download PDF

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Publication number
US4297149A
US4297149A US06/146,380 US14638080A US4297149A US 4297149 A US4297149 A US 4297149A US 14638080 A US14638080 A US 14638080A US 4297149 A US4297149 A US 4297149A
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United States
Prior art keywords
devices
annealing
temperature
breakdown voltage
sipos
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Expired - Lifetime
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US06/146,380
Inventor
Patrick R. Koons
John M. S. Neilson
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Intersil Corp
RCA Corp
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RCA Corp
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Priority to US06/146,380 priority Critical patent/US4297149A/en
Priority to IT20995/81A priority patent/IT1137677B/en
Priority to YU01089/81A priority patent/YU108981A/en
Priority to SE8102651A priority patent/SE8102651L/en
Priority to DE19813116998 priority patent/DE3116998A1/en
Priority to JP6680881A priority patent/JPS572529A/en
Application granted granted Critical
Publication of US4297149A publication Critical patent/US4297149A/en
Assigned to INTERSIL CORPORATION reassignment INTERSIL CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: HARRIS SEMICONDUCTOR PATENTS, INC.
Assigned to CREDIT SUISSE FIRST BOSTON, AS COLLATERAL AGENT reassignment CREDIT SUISSE FIRST BOSTON, AS COLLATERAL AGENT SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: INTERSIL CORPORATION
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/18Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/324Thermal treatment for modifying the properties of semiconductor bodies, e.g. annealing, sintering
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/18Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/31Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
    • H01L21/3105After-treatment
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10STECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S257/00Active solid-state devices, e.g. transistors, solid-state diodes
    • Y10S257/905Plural dram cells share common contact or common trench
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10STECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S438/00Semiconductor device manufacturing: process
    • Y10S438/958Passivation layer

Definitions

  • This invention relates to the field of passivation of high voltage semiconductor devices.
  • This problem is ameliorated by annealing the devices at a temperature above 525° C. prior to metallization and by alloying the metallization at a temperature of less than 425° C. for less than ten minutes above 400° C. Full voltage capability is recovered by annealing at above 550° C. prior to metallization.
  • SiPOS oxygen doped polycrystalline silicon
  • the devices are subsequently metallized with aluminum and were alloyed in a tube furnace set at 450° C.
  • the resulting finished devices had subsequently lower breakdown voltages than expected.
  • the cause of the problem was not understood because it was assumed that the metal alloying temperatures were low enough that they would not affect a SiPOS layer which had been annealed at 900° C.
  • subsequent experimentation established that the maximum breakdown voltage is obtained by minimizing the time the devices spend in the 400° C. to 525° C. temperature range following the SiPOS anneal.
  • the device breakdown voltage does degrade in the 400° C. to 425° C. temperature range, but significant degradation does not accumulate until after more than ten minutes total time in this range.
  • a device of this type whose breakdown voltage has decreased to 1300 volts will recover 90 to 95% of its original breakdown voltage if it is annealed at 525° C. for one-half hour.
  • Such a device (1300 v breakdown) annealed at 550° C. for one-half hour will recover its full initial 1700 volt breakdown voltage.
  • the maximum breakdown voltage is provided by avoiding permitting the devices to soak in the 400°-525° C. temperature range subsequent to SiPOS anneal or by annealing the devices at above 550° C. prior to metallization if they have been permitted to sit in a 400°-525° C. environment.
  • This anneal is carried out in a tube furnace set at 550° C.
  • the devices are pulled directly from the furnace to ambient air in order that they will cool rapidly through the 525° C.-400° C. temperature range.
  • the devices are then metallized with aluminum or other appropriate metallization and the metallization is alloyed in a belt furnace with its peak temperature set at less than 425° C. for a maximum time of ten minutes above 400° C.
  • the resulting devices have substantially their entire 1700 volt breakdown voltage.
  • the annealing at 550° C. is preferably utilized as a pre-metallization treatment to assure that devices will have maximum breakdown voltage even if through some error, oversight, or furnace loading effects in previous steps they have soaked in the forbidden temperature range at some point subsequent to the SiPOS anneal.
  • Subsequent steps which make an annealing advisable include the fusing of a glass overcoat over the SiPOS junction passivation under conditions which may result in excessive soaking in the 400° C. to 525° C. temperature range.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Manufacturing & Machinery (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Internal Circuitry In Semiconductor Integrated Circuit Devices (AREA)
  • Electrodes Of Semiconductors (AREA)
  • Formation Of Insulating Films (AREA)

Abstract

The breakdown voltage of high voltage semiconductor devices passivated with SiPOS deteriorates if the devices are allowed to soak at temperatures in the 400° C. to 525° C. range. The original breakdown voltage is recovered by annealing the devices at a temperature of above about 550° C. prior to metallization and alloying the metal at less than 425° C.

Description

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the field of passivation of high voltage semiconductor devices.
2. Prior art
Many passivation techniques have been utilized in prior art high voltage semiconductor devices. Passivation of the high voltage junction by depositing an oxygen doped polycrystalline silicon layer on the surface of the device bridging the junction has become a popular way to passivate semiconductor devices. For integrated circuits and other low voltage devices this is proved to be an effective passivation technique. As a result it has been used for the passivation of high voltage semiconductor devices.
3. The problem
In attempting to apply oxygen doped polycrystalline silicon as a passivation technique to high voltage semiconductor devices such as deflection transistors which have a design breakdown voltage of 1700 volts, we have discovered that the breakdown voltage of these devices is dependent on the thermal history of the device. We have found that allowing the devices to sit at 450° C. for as little as ten minutes will decrease the breakdown voltage by as much as 200 volts. Longer times will produce greater degradation of the breakdown voltage. We have determined that the primary range of temperature sensitivity for our devices is in the 400° C. to 525° C. range and that the most rapid deterioration occurs in the range of 450° C. to 500° C.
SUMMARY OF THE INVENTION
This problem is ameliorated by annealing the devices at a temperature above 525° C. prior to metallization and by alloying the metallization at a temperature of less than 425° C. for less than ten minutes above 400° C. Full voltage capability is recovered by annealing at above 550° C. prior to metallization.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Our 1700 volt breakdown voltage devices use depletion moats at the high voltage junction. The oxygen doped polycrystalline silicon (SiPOS) passivation layers on these devices are about 5500 Angstroms thick and are deposited at about 600° C. from source gases comprising about 20% N2 O and about 80% SiH4. This SiPOS layer is deposited directly on the semiconductor surface. Subsequent to its deposition the SiPOS layer is annealed at 900° C. for from one-half hour to one hour.
The devices are subsequently metallized with aluminum and were alloyed in a tube furnace set at 450° C. The resulting finished devices had subsequently lower breakdown voltages than expected. Initially the cause of the problem was not understood because it was assumed that the metal alloying temperatures were low enough that they would not affect a SiPOS layer which had been annealed at 900° C. However, subsequent experimentation established that the maximum breakdown voltage is obtained by minimizing the time the devices spend in the 400° C. to 525° C. temperature range following the SiPOS anneal.
The device breakdown voltage does degrade in the 400° C. to 425° C. temperature range, but significant degradation does not accumulate until after more than ten minutes total time in this range.
If a device having an initial breakdown voltage of 1700 volts is allowed to soak at 450° C. for ten minutes the breakdown voltage will reduce to about 1500 volts. Continued exposure to this temperature results in continuing reduction in the breakdown voltage with an asymptote of about 800 volts.
It is thought that the decrease in breakdown voltage may be a result of changes in the types of oxygen-silicon bonds present in the oxygen doped polycrystalline silicon.
A device of this type whose breakdown voltage has decreased to 1300 volts will recover 90 to 95% of its original breakdown voltage if it is annealed at 525° C. for one-half hour. Such a device (1300 v breakdown) annealed at 550° C. for one-half hour will recover its full initial 1700 volt breakdown voltage.
We have found that the maximum breakdown voltage is provided by avoiding permitting the devices to soak in the 400°-525° C. temperature range subsequent to SiPOS anneal or by annealing the devices at above 550° C. prior to metallization if they have been permitted to sit in a 400°-525° C. environment. This anneal is carried out in a tube furnace set at 550° C. At the end of the annealing time, the devices are pulled directly from the furnace to ambient air in order that they will cool rapidly through the 525° C.-400° C. temperature range. The devices are then metallized with aluminum or other appropriate metallization and the metallization is alloyed in a belt furnace with its peak temperature set at less than 425° C. for a maximum time of ten minutes above 400° C. The resulting devices have substantially their entire 1700 volt breakdown voltage.
The annealing at 550° C. is preferably utilized as a pre-metallization treatment to assure that devices will have maximum breakdown voltage even if through some error, oversight, or furnace loading effects in previous steps they have soaked in the forbidden temperature range at some point subsequent to the SiPOS anneal. When cooling the devices at the end of the SiPOS anneal it is preferred to cool them slowly to 550° C. and then rapidly through the problem temperature range. This substantially minimizes the problem of breakdown voltage loss in the event that subsequent high temperature steps are not performed.
Subsequent steps which make an annealing advisable include the fusing of a glass overcoat over the SiPOS junction passivation under conditions which may result in excessive soaking in the 400° C. to 525° C. temperature range.
A processing technique for obtaining maximum breakdown voltage for semiconductor devices which are passivated with SiPOS has been described. Those skilled in the art will be able to modify the preferred embodiment in view of the teachings of the specification without departing from the spirit of the invention as defined in appended claims.

Claims (6)

What is claimed is:
1. In a process of fabricating a semiconductor device having oxygenated polycrystalline silicon passivation layers the improvement comprising:
annealing the devices at at least 525° C. prior to metallization;
cooling the devices rapidly through the 500° C. to 450° C. temperature range at the end of said annealing;
preventing the devices from subsequently being heated to any temperature higher than 425° C.; and
preventing the devices from being exposed to any temperature above 400° C. for longer than a total of ten minutes subsequent to the annealing whereby the devices will have near the maximum breakdown voltage of which their structure is capable.
2. The method recited in claim 1 wherein:
said annealing step is performed at a temperature of at least 550° C.
3. The method recited in claim 1 wherein:
said annealing step is carried out for a period of at least one-half hour.
4. The method recited in claim 1 wherein subsequent to metal deposition:
the metal is alloyed with the semiconductor at a temperature in the range between 400° C. and 425° C.
5. The method recited in claim 1 wherein:
said rapid cooling is through the 525° C. to 400° C. temperature range.
6. A method of maximizing the breakdown voltage of semiconductor devices having oxygenated polycrystalline silicon passivation layers comprising:
annealing said devices at a temperature above 525° C. prior to metallizing the devices;
cooling said devices rapidly through the temperature range 525° C. to 425° C. following said annealing;
preventing said devices from being heated to above 425° C. subsequent to said annealing.
US06/146,380 1980-05-05 1980-05-05 Method of treating SiPOS passivated high voltage semiconductor device Expired - Lifetime US4297149A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
US06/146,380 US4297149A (en) 1980-05-05 1980-05-05 Method of treating SiPOS passivated high voltage semiconductor device
IT20995/81A IT1137677B (en) 1980-05-05 1981-04-08 HIGH VOLTAGE SEMICONDUCTIVE DEVICE, PASSIVATED WITH A LAYER OF POLYCRYSTALLINE SILICON DROUGHT WITH OXYGEN
SE8102651A SE8102651L (en) 1980-05-05 1981-04-27 SEMICONDUCTOR DEVICE
YU01089/81A YU108981A (en) 1980-05-05 1981-04-27 Method of making semiconductor devices
DE19813116998 DE3116998A1 (en) 1980-05-05 1981-04-29 "METHOD FOR PRODUCING A SEMICONDUCTOR COMPONENT"
JP6680881A JPS572529A (en) 1980-05-05 1981-04-30 Method of manufacturing high voltage semiconductor device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US06/146,380 US4297149A (en) 1980-05-05 1980-05-05 Method of treating SiPOS passivated high voltage semiconductor device

Publications (1)

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US4297149A true US4297149A (en) 1981-10-27

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US (1) US4297149A (en)
JP (1) JPS572529A (en)
DE (1) DE3116998A1 (en)
IT (1) IT1137677B (en)
SE (1) SE8102651L (en)
YU (1) YU108981A (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4349408A (en) * 1981-03-26 1982-09-14 Rca Corporation Method of depositing a refractory metal on a semiconductor substrate
US4516145A (en) * 1983-08-31 1985-05-07 Storage Technology Partners Reduction of contact resistance in CMOS integrated circuit chips and the product thereof
US4580156A (en) * 1983-12-30 1986-04-01 At&T Bell Laboratories Structured resistive field shields for low-leakage high voltage devices
USH665H (en) 1987-10-19 1989-08-01 Bell Telephone Laboratories, Incorporated Resistive field shields for high voltage devices
US5374843A (en) * 1991-05-06 1994-12-20 Silinconix, Inc. Lightly-doped drain MOSFET with improved breakdown characteristics

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE300472B (en) * 1965-03-31 1968-04-29 Asea Ab
US3674995A (en) * 1970-08-31 1972-07-04 Texas Instruments Inc Computer controlled device testing and subsequent arbitrary adjustment of device characteristics
US3971061A (en) * 1973-05-19 1976-07-20 Sony Corporation Semiconductor device with a high breakdown voltage characteristic
US4001873A (en) * 1973-12-26 1977-01-04 Mitsubishi Denki Kabushiki Kaisha Semiconductor device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE300472B (en) * 1965-03-31 1968-04-29 Asea Ab
US3674995A (en) * 1970-08-31 1972-07-04 Texas Instruments Inc Computer controlled device testing and subsequent arbitrary adjustment of device characteristics
US3971061A (en) * 1973-05-19 1976-07-20 Sony Corporation Semiconductor device with a high breakdown voltage characteristic
US4001873A (en) * 1973-12-26 1977-01-04 Mitsubishi Denki Kabushiki Kaisha Semiconductor device

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4349408A (en) * 1981-03-26 1982-09-14 Rca Corporation Method of depositing a refractory metal on a semiconductor substrate
US4516145A (en) * 1983-08-31 1985-05-07 Storage Technology Partners Reduction of contact resistance in CMOS integrated circuit chips and the product thereof
US4580156A (en) * 1983-12-30 1986-04-01 At&T Bell Laboratories Structured resistive field shields for low-leakage high voltage devices
USH665H (en) 1987-10-19 1989-08-01 Bell Telephone Laboratories, Incorporated Resistive field shields for high voltage devices
US5374843A (en) * 1991-05-06 1994-12-20 Silinconix, Inc. Lightly-doped drain MOSFET with improved breakdown characteristics

Also Published As

Publication number Publication date
IT8120995A0 (en) 1981-04-08
IT1137677B (en) 1986-09-10
IT8120995A1 (en) 1982-10-08
SE8102651L (en) 1981-11-06
DE3116998A1 (en) 1982-02-04
JPS572529A (en) 1982-01-07
YU108981A (en) 1983-09-30

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